A representation of a reservoir that incorporates all data pertinent to its ability to store and produce oil and gas. Geoscientists and engineers use reservoir modeling to simulate the movement of the oil and gas under various circumstances to ultimately determine optimal production techniques for the reservoir. The ultimate aim of reservoir modeling is to provide a forecast of reservoir behavior under production conditions. A reservoir model is a mathematical simulation which predicts the production performance of the field and is used to formulate an optimum development plan. One needs to remember this is a model or an estimate, not reality.